This invention relates to an image forming apparatus, more particularly an image forming apparatus such as, but not limited to, a page printer which includes an optical signal generator (i.e., optical beam write device) and which is part of a printing system having a paper feeder, a sorter and/or a jogger.
An image forming apparatus such as an optical beam write-type page printer includes a photosensitive drum positioned along a paper path within the printer which extends from a sheet feeding port to a sheet exhausting port. The surface conductivity of the photosensitive drum changes based on an optical beam applied thereto produced by an optical signal generator (i.e., optical beam write device). The printer also includes an electrostatic charging device for uniformly charging the surface of the photosensitive drum. The optical beam, which is representative of the image to be formed, passes through an optical beam radiating window prior to striking the surface of the photosensitive drum.
Initially, the photosensitive drum is uniformly electrically charged, either negatively or positively, by the electrostatic charging device. As the photosensitive drum continues to rotate, certain areas thereof are irradiated with light representing the image information generated by the optical signal generator. A static latent image formed on the surface of the photosensitive drum then passes a toner developing device. Toner is deposited on the photosensitive drum in accordance with the static latent image to form a toner image. The toner image is then transferred to a recording medium (i.e., sheet of paper) by a transfer device. Excess toner which has not been transferred onto the sheet of paper is removed by a cleaning device (i.e., toner recovering device).
Such image forming apparatus produces, at a high speed, a high quality pattern of characters based on the principles of xerography. A relatively small number of pages is generated using such printers. When a large number of pages are to be printed, optional devices such as an automatic sheet feeder for feeding the sheets of paper and a sorter for sorting the sheets of paper are used in combination with the printer. Adding the feeder and sorter to the printer requires the configuration of the printer be standardized so as to accommodate the addition of these optional features to the printer.
The addition of an automatic sheet feeder and sorter to the printer requires that the printer include a host device. The host device, which is typically a small computer, provides data to the automatic sheet feeder for feeding sheets of paper to the printer and information to the sorter for sorting the sheets of paper from the printer. Since printers vary in configuration (i.e., specifications), optional devices such as automatic sheet feeders and sorters when used with these different printers must also vary in design (i.e., configuration).
It is therefore desirable to provide an image forming apparatus which can be used with a number of different types of optional devices such as, but not limited to, automatic sheet feeders, sorters and the like. In particular, the image forming apparatus should have a high degree of compatibility with a variety of different types of optional devices.